I have not heard GR01 but have many IEMs with the same TWFK driver. I would guess it is not as warm with less bass extension and mid bass warmth and presence. Will have more transparent and detailed mids with a tad more presence and the same will app for treble.
this is a comparison with the R-50 which is said to sound the same as GR01.
the MA2 is complete across the spectrum and warmer and more enjoyable but the GR01/R-50 would probably be said to be more technical.